Novel Platelet ADP P2Y12 Inhibitors in the Treatment of Acute Coronary Syndrome

Efficacy, Safety, and Role of Antiplatelet Drugs in the Management of Acute Coronary Syndrome: A Comprehensive Review of Literature

Acute coronary syndrome (ACS) is a complex condition characterized by myocardial ischemia or infarction which can lead to significant morbidity and death. Antiplatelet drugs play a crucial role in the management of ACS and have been shown to minimize the incidence of significant adverse cardiovascular events and recurrent myocardial infarction (MI). This comprehensive literature review is intended to summarize current information on the effectiveness, safety, and function of frequently used antiplatelet medications in treating ACS. Aspirin, clopidogrel, prasugrel, ticagrelor, abciximab, tirofiban, dipyridamole, cilostazol, and novel antiplatelets are included in the review. Aspirin's effectiveness as a first-line antiplatelet medication in ACS is well established. It has significantly lowered the risk of serious adverse cardiovascular events. Clopidogrel, prasugrel, and ticagrelor are P2Y12 receptor inhibitors found to lower the incidence of recurrent ischemia episodes in ACS patients. Using glycoprotein IIb/IIIa inhibitors such as abciximab, tirofiban, and eptifibatide is effective in managing ACS, especially in high-risk patients. Dipyridamole effectively reduces the risk of recurrent ischemic events in patients with ACS, particularly when used with aspirin. Cilostazol, a phosphodiesterase III inhibitor, has also been shown to reduce the risk of major adverse cardiovascular events (MACE) in patients with ACS. Antiplatelet drugs' safety in managing ACS has also been well established. Aspirin is generally well-tolerated with a low risk of adverse effects, although the risk of bleeding events, particularly gastrointestinal bleeding, cannot be eliminated. The P2Y12 receptor inhibitors have been associated with a small increase in the risk of bleeding events, particularly in patients with a high risk of bleeding. The glycoprotein IIb/IIIa inhibitors are associated with a higher risk of bleeding than other antiplatelet drugs, especially in high-risk patients. To summarize, antiplatelet drugs play a crucial role in the management of ACS, and the efficacy and safety of these drugs have been well-established in the literature. The choice of antiplatelet drugs will depend on the patient's risk factors, including age, comorbidities, and bleeding risk. The novel antiplatelets may offer new therapeutic options for managing ACS, and further studies are needed to determine their role in managing this complex condition.

Potent and Orally Bioavailable Antiplatelet Agent, PLD-301, with the Potential of Overcoming Clopidogrel Resistance

PLD-301, a phosphate prodrug of clopidogrel thiolactone discovered by Prelude Pharmaceuticals with the aim to overcome clopidogrel resistance, was evaluated for its in vivo inhibitory effect on ADP-induced platelet aggregation in rats. The potency of PLD-301 was similar to that of prasugrel, but much higher than that of clopidogrel. The results of pharmacokinetic analysis showed that the oral bioavailability of clopidogrel thiolactone converted from PLD-301 was 4- to 5-fold higher than that of the one converted from clopidogrel, suggesting that in comparison with clopidogrel, lower doses of PLD-301 could be used clinically. In summary, PLD-301 presents a potent and orally bioavailable antiplatelet agent that might have some advantages over clopidogrel, such as overcoming clopidogrel resistance for CYP2C19-allele loss-of-function carriers, and lowering dose-related toxicity due to a much lower effective dose.

Antithrombotic activities of ferulic acid via intracellular cyclic nucleotide signaling

Ferulic acid (FA) produces protective effects against cardiovascular dysfunctions. However, the mechanisms of FA is still not known. Here we examined the antithrombotic effects of FA and its potential mechanisms. Anticoagulation assays and platelet aggregation was evaluated in vitro and in vivo. Thromboxane B2 (TXB2), cyclic adenosine monophosphate(cAMP), and cyclic guanosine monophosphate (cGMP) was determined using enzyme immunoassay kits. Nitric oxide (NO) production was measured using the Griess reaction. Protein expression was detected by Western blotting analysis. Oral administration of FA prevented death caused by pulmonary thrombosis and prolonged the tail bleeding and clotting time in mice,while, it did not alter the coagulation parameters, including the activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT). In addition, FA (50-200 µM) dose-dependently inhibited platelet aggregation induced by various platelet agonists, including adenosine diphosphate (ADP), thrombin, collagen, arachidonic acid (AA), and U46619. Further, FA attenuated intracellular Ca(2)(+) mobilization and TXB2 production induced by the platelet agonists. FA increased the levels of cAMP and cGMP and phosphorylated vasodilator-stimulated phosphoprotein (VASP) while decreased phospho-MAPK (mitogen-activated protein kinase) and phosphodiesterase (PDE) in washed rat platelets, VASP is a substrate of cyclic nucleotide and PDE is an enzyme family responsible for hydrolysis of cAMP/cGMP. These results suggest that antithrombotic activities of FA may be regulated by inhibition of platelet aggregation, rather than through inhibiting the release of thromboplastin or formation of thrombin. The mechanism of this action may involve activation of cAMP and cGMP signaling.

Role of Pannexin-1 hemichannels and purinergic receptors in the pathogenesis of human diseases

In the last decade several groups have determined the key role of hemichannels formed by pannexins or connexins, extracellular ATP and purinergic receptors in physiological and pathological conditions. Our work and the work of others, indicate that the opening of Pannexin-1 hemichannels and activation of purinergic receptors by extracellular ATP is essential for HIV infection, cellular migration, inflammation, atherosclerosis, stroke, and apoptosis. Thus, this review discusses the importance of purinergic receptors, Panx-1 hemichannels and extracellular ATP in the pathogenesis of several human diseases and their potential use to design novel therapeutic approaches.

Progress in platelet blockers: the target is the P2Y12 receptor

The considerable progress in P2Y12-platelet blockers has important perioperative implications due to a family of novel agents beyond clopidogrel. Although prasugrel is more potent than clopidogrel due to more efficient hepatic metabolism, it is limited clinically by its irreversibility and bleeding risks. Ticagrelor, as the first approved direct and reversible oral P2Y12 blocker, still is limited clinically by its novel side-effect profile. Intravenous reversible P2Y12 blockade is possible now with both cangrelor and elinogrel, although both agents are still in clinical development. Furthermore, elinogrel offers the possibility of both oral and parenteral P2Y12 blockade with a single agent. Future trials likely will continue to evaluate and compare the safety and efficacy of these agents in multiple clinical settings, including the perioperative period.